Recipient Organization
UNIV OF IDAHO
875 PERIMETER DRIVE
MOSCOW,ID 83844-9803
Performing Department
Soil and Water Systems
Non Technical Summary
To address natural and agronomic resourceissues, research at the landscape scale is needed to investigate the current nutrient (carbon, nitrogen, phosphorus) pools in soils of Idaho, quantify nutrient turnover rates, and identify the abiotic drivers of their mobilization and transport to sustain agricultural and resource management in the state. This research focuses on large scale land-use management and its influence on soil nutrients. Massive soil erosion resulting from agricultural tillage has led to conservation practices that can be investigated at a landscape scale. The application of fertilizers exceeding plant uptake has resulted in phosphorus legacies that can have cascading downstream effects. These signals of land-use history can be detected in soils and sediments using novel techniques that integrate over spatial and temporal scales.The overall goal is to establish a research and scholarly program that lays the foundation for a robust understanding of nutrient cycling of the region that is relevant to Idaho's producers and stakeholders through field experiments and monitoring, method and course development, and updated management guidelines.The specific goals of the project presented below are to better understand the impact of no-till agricultural fields as compared to conventional till at the watershed and field scale by 1) quantifying soil nutrient (N and P) transformations and subsequent soil losses, and 2) identifying the different sources of carbon and nutrients seasonally using molecular techniques (3).
Animal Health Component
80%
Research Effort Categories
Basic
10%
Applied
80%
Developmental
10%
Goals / Objectives
The overall goal is to establish a research and scholarly program that lays the foundation for a robust understanding of nutrient cycling of the region that is relevant to Idaho's producers and stakeholders through field experiments and monitoring, method and course development, and updated management guidelines.The specific goals of the project presented below are to better understand the impact of no-till agricultural fields as compared to conventional till at the watershed and field scale by 1) quantifying soil nutrient (N and P) transformations and subsequent soil losses, and 2) identifying the different sources of carbon and nutrients seasonally using molecular techniques. Project Objectives:Quantify nutrient retention and water quality in two watersheds that contrast in agricultural management.Quantify and compare field-scale soil, plant, and soil water phosphorus and nitrogen spatial patterns in no-till and conventional till.Develop a method to trace phosphorus through the plant-soil-water system in agricultural catchments using the δ18O of ortho-phosphate.
Project Methods
Watershed-scale assessment of water quality and nutrient retention in conservation agricultureObjective 1.Quantify nutrient retention and water quality in two watersheds that contrast with each other in respect to predominate agricultural management practices.Work Plan:The Palouse Conservation District (PCD) has established a water quality monitoring program in two watersheds, one under predominately no-till management and the other under conventional till. We will use the sediment record from different positions in the watershed to assess the overall impact of no-till on water quality, determine catchment wide erosion rates, and quantify watershed level nutrient turnover times. There are two project tasks for the first phase, 1) use two years of water quality data to estimate carbon, nitrogen, and phosphorus mean residence times using a steady-state model, and 2) use stable (d13C,??15N, ? P18O) and radio isotopes (14C,10Be) from stream sediments and cores to calculate nutrient turnover within different points in each watershed.Data Interpretation and UseThe comparison of age and transit time from the model and the empirical isotope estimates will indicate potential gaps in the data as well as the PCD monitoring plan. The comparison of age and transit time between the two watersheds will indicated the effectiveness of the no-till treatment in retaining nutrients compared to the conventional till dominated watershed. Erosion estimates will provide direct evidence of the effectiveness of conservation agriculture in preventing soil loss. The potential to model nutrient transit times over the sediment record may be possible if the model-isotope relationship is sufficiently coordinated.Efforts:I will present these results at professional and stakeholder conferences and workshops via oral and poster presentations. I will employ an MS student to assist on this work; I also anticipate undergraduate help in field sampling and sample processing in the lab. I will share the results and solicit feedback from U of I Extension and local conservation districts, thus extending the dialogue beyond the classroom.Evaluation:For this project I will mentor one graduate student, although additional students are anticipated. The dataset compiled will be helpful in designing updated nutrient guidelines in the region. This information will serve local producers as well as a number of growers in the dryland agricultural region of the iPNW. I anticipate the approach developed here will be a useful tool to assess land management impacts or effectiveness at the watershed scale.Objective 2.Quantify and compare soil, plant, and soil water phosphorus and nitrogen spatial patterns across practices that enhance soil healthWork plan:I will sample two catchments under different tillage practices. Currently, both catchments are monitored for total phosphorus, orthophosphate (dissolved reactive phosphorus), and total nitrogen as well as a suite of ions found in water from a tile line, overland surface flow, and a buried lysimeter.Data Interpretation and UseLysimeter data will help in identifying the nutrient concentrations in the mobile pool of the soil. I expect the resin bags to give a more integrative measure of the soil nutrient availabilities. Data will be interpreted based on the no-till versus conventional tillage treatments and repeated sampling measurements implemented in a mixed-effects model. Other analyses will concern differences between measurement types (lysimeter and resin bags) and the concentration depth profile changes over the growing season and precipitation events.The data will be used for student theses, peer-reviewed publications, and coursework development at first. The data will also contribute to a larger overall effort to quantify soil nutrient pools and their dynamics as they correspond to plant yield, thus achieving a metric of plant efficiency.Efforts:I will enroll a MS student to carry out field research, data analysis, publication production, and mentoring of undergraduate students. One laboratory technician will be involved to help in analyzing soil and water samples, performing data quality checks, and data archiving. The MS student will use the research project as a vehicle to develop communication skills through poster and oral presentations at conferences, lectures, and by developing a storyboard or webinar of the project. As faculty in the campus-wide Water Resources Program, I will share findings with students and colleagues in this program. I will also base future proposals on the results from this work to build upon the program started with this project.Evaluation:For this project, I will mentor at least one graduate student researcher, although additional students are anticipated. I expect the results of this project to clarify the intrinsic soil processes behind the increase in P levels that occur in no-till. This work will serve as a platform for submitted or soon to be submitted research on agroecology (USDA NIFA NNH), conservation (USDA NRCS CIG), and biodiversity.Objective 3.Use the δ18O of ortho-phosphate to trace phosphorus through the plant-soil-water system in agricultural catchments.Work plan:Overall, I want to quantify the δ18O signature of major phosphorus (P) pools (plants, soil, soil water, tile drainage) in the CAF spatially and temporally in till vs no till catchments. P will also be extracted from soil at the same depths we place lysimeters (or other device) when measured P concentrations are large enough. Other P pools important to characterize on a seasonal basis are precipitation, plant biomass (leaves and roots), and the fertilizers used (organic and inorganic).Data Interpretation and Use: The equilibrium value of δ18O will be estimated using the tile drain water temperature and air temperature at the CAF weather station. Tile line flow will also assist in the interpretation of phosphate δ18O patterns as related to potential isotopic sources. The data will be used directly to understand the different sources contributing to the DRP and organic P collected at the tile line drain. A comparison of the no-till and conventional till catchments will allow testing of the null hypothesis that there are no detectable differences in the isotopic signature of phosphate emitted from the tile drain over a season.The data will be used for student theses, peer-reviewed publications, and coursework development (laboratory). The data will also contribute to a larger overall effort to quantify the impact of no-till on nutrient mineralization and loss from agricultural soils.Efforts:I will enroll a MS student to carry out field research, data analysis, publication production, and mentoring of undergraduate students. One laboratory technician will be involved to help in analyzing soil and water samples, performing data quality checks, and data archiving. The MS student will use the research project as a vehicle to develop communication skills through poster and oral presentations at conferences, and lectures. As faculty in the Water Resources Program, I will also have the opportunity to share findings with students and colleagues in this program. I anticipate presenting these results at national or international conferences. In addition to the efforts listed above, I will also base future proposals on the results from this work to build upon the program started with this project.Evaluation:For this project I will mentor at least one graduate student researcher, although additional students are anticipated, from which publications, reports, and presentations will result. With the development of this method, a new laboratory based tool will be made available to ongoing and proposed projects on tracing phosphorus in terrestrial and aquatic ecosystems.